Bean aphid (Aphis fabae)
Green peach aphid (Myzus persicae)
Willow-carrot aphid (Cavariella aegopodii)
Pest description and crop damage The green peach aphid is slender, dark green to yellow, and has no waxy bloom. The wingless form of the green peach aphid is pale green. The winged form has a black head and thorax. It is primarily an early year pest and transmits virus diseases. The willow-carrot aphid is pale greenish yellow. The winged form is pale yellow marked with black. Its primary host is willow, but it feeds on carrots during the summer. The bean aphid is dark olive green to black with light-colored legs. It is usually more of an early season pest.
Aphids feed on carrot foliage, but they are a key pest because they can transmit diseases such as motley dwarf virus. In general, aphids damage plants by sucking plant sap, which causes heavily infested leaves to curl and stunt; by excreting honeydew, which causes sticky, shiny leaves to turn black because of a sooty-mold fungus growth; and by spreading plant diseases (a large number of viruses are spread by aphids).
Biology and life history
Pest monitoring Check fields frequently after seedlings emerge. If aphids become numerous, increase the frequency of sampling. Aphids often are concentrated in hot spots or near the field margin. Note the presence of any hot spots, but avoid sampling only those areas. Also, be sure to look for evidence of biological control; i.e., the presence of predators, parasites (aphid mummies), and disease. Aphid flights are most common during periods of moderate temperatures (60° to 80°F). Monitor fields particularly closely during April and May.
Many parasites and predators attack aphids. Early year aphids have many natural enemies that frequently bring them under control later in the year. Among the more common predators are lady beetles and their larvae, lacewing larvae, and syrphid fly larvae. Populations of green peach aphids are reduced in winter by a parasitic fungus, Entomophthora aphidis.
Monitor the proportion of aphid mummies relative to unparasitized aphids and the numbers of predators such as lady beetles. If the proportion of mummies is increasing, or predators appear to be gaining control, and aphid populations are not yet damaging, avoid sprays that will disrupt these natural enemies. Most materials for aphid control are highly disruptive of natural enemy populations.
Destroy infested crops immediately after harvest to prevent aphid dispersal. Destroying weed hosts late in the year may help destroy overwintering populations. Populations tend to be higher in crops that are fertilized liberally with nitrogen. Home gardeners can often get effective control by washing aphids with a strong stream of water.
Management-chemical control: HOME USE
Apply to both tops and undersides of leaves.
- azadirachtin (neem extract)-Some formulations are OMRI-listed for organic use.
- Beauvaria bassiana-Some formulations are OMRI-listed for organic use.
- insecticidal soap-May require several applications. Some formulations are OMRI-listed for organic use.
- kaolin-Applied as a spray to foliage It acts as a repellent to some insect pests. Some formulations are OMRI-listed for organic use.
- plant-derived essential oils (clove, rosemary, etc.)-Some have demonstrated efficacy on aphids. Some formulations are OMRI-listed for organic use.
- pyrethrins (often combined with other ingredients)-Some formulations are OMRI-listed for organic use.
Management-chemical control: COMMERCIAL USE
- Beauveria bassiana (Mycotrol O) at 0.25 to 1 quart/100 gal spray volume. PHI 0 days. REI 4 hr. OMRI-listed for organic use.
- bifenthrin (Brigade) at 0.08 to 0.1 lb ai/a. PHI 21 days. REI 12 hr. Retreatment interval 7 days. Do not exceed 0.5 lb ai/a per season.
- borate complex (Prev-Am) applied as a 0.8% solution. Spray to complete coverage. PHI 1 day. REI 12 hr. Retreatment interval 7-10 days. OMRI-listed for organic use.
- Chromobacterium subtsugae (Grandevo) at 0.6 to 0.9 lb ai/a per 100 gal. PHI 0 days. REI 4 hr. OMRI-listed for organic use.
- deltamethrin (Battalion) at 0.012 to 0.028 lb ai/a. PHI 3 days. REI 12 hr. Retreatment interval 3 days. Do not exceed 0.14 lb ai/a per season.
- flonicamid (Beleaf) at 0.062 to 0.089 lb ai/a. PHI 3 days. REI 12 hr. Retreatment interval 7 days. Do not exceed 0.267 lb ai/a per season. Limit to 3 applications.
- imidacloprid (Admire) at 0.156 to 0.375 lb ai/a, or 0.011 to 0.027 lb ai/1,000 row feet. Soil application only. PHI 21 days. REI 12 hr. One treatment per season only. Do not exceed 0.375 lb ai/a per year.
- imidacloprid (Provado, Prey) at 0.044 lb ai/a. PHI 7 days. REI 12 hr. Do not exceed three treatments per season. Do not exceed 0.13 lb ai/a per season.
- insecticidal soap (M-Pede) at 1 to 2% solution. Potassium salts of fatty acids. See label for gal/a. PHI 0 days. REI 12 hr.
- malathion (numerous products) at 1 to 1.25 lb ai/200 gal. PHI 7 days. REI 12 hr.
- thiamethoxam (Actara) at 0.023 to 0.047 lb ai/a. REI 12 hr. PHI 7 days. Do not exceed 0.125 lb ai/a per year. Retreatment interval 7 days.
- thiamethoxam (Platinum) at 0.078 to 0.188 lb ai/a soil applied. REI 12 hr. Do not exceed 0.188 lb ai/a per season.
- zeta-cypermethrin (Mustang) at 0.04 to 0.05 lb ai/a. PHI 1 day. REI 12 hr. Do not exceed 0.3 lb ai/a per year.